Note: Descriptions are shown in the official language in which they were submitted.
APPARATUS AND MEl~OD
FOR PRECISELY DISPENSING SOLID MATERIALS
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This invention relates to materials handling
equipment and more particularly to equipment for
accurately discharging the entire contents of a
container.
~ck~round Ar~
Materials for use in m~nufacturing processes,
particularly for use in manufacturing processes
comprising the mixing or reacting of the materials, are
typically packaged in containers. Various specialized
mechanisms have been proposed for handling these
containers.
For example, U.S. 4,095,707 relates to a transfer
mechanism for dumping the contents of a shipping drum
containing a powdery substance into a mixing vessel
without the release of any dust or ~smoke.~ The mixing
vessel is turned upside down over the open shipping
drum. A seal is formed between the top of the shipping
drum and the mixing vessel, and the combination is
rotated 180 so that the mixing vessel returns to its
operative position, and the contents of the shipping
drum are transferred to the mixing vessel. The
shippin~ drum may have a plastic liner.
U.S. 4,946,071 relates to equipment for
discharging particular solid materials from
intermediate bulk containers comprising an outer,
reusable bag and an inner liner having a spout portion.
The spout is clamped over the mouth of a discharge
duct.
U.S. 1,953,042 relates to a bag emptying device
designed to prevent foreign objects on the outside of
the bag from being introduced along with the contents
of the bag. The bag is placed in a cylindrical casing,
and the top of the bag is fastened to the top of the
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casing. I~e bag can then be dumped without having
material clinging to the outside of the bag being
emptied into a bin or other container.
Thus, various equipment for the handling of
containers has been proposed. A special problem
arises, however, during manufacturing processes that
require accurate amounts of various materials to be
mixed or reacted. These materials are generally
packaged in a specified amount in a container. It is
essential that all of the rnaterial in the container be
transferred to the mixing vessel in order to insure
that the end product meets specifications. With the
advent of automatic handling equipment in manufacturing
lines, it is especially imperative to provide equipment
which reproducibly delivers the entire contents of a
container, without the necessity for human intervention
or monitoring.
Because shipping containers vary in weight, and
since the accuracy of delivery must be quite high in
many manufacturing processes, a system based on tare
weight is inadequate. Similarly, systems which detect,
visually or otherwise, some property of the material in
the container, and thereby determine whether any of th~
material remains in the container, are unworkable where
the same apparatus is used to empty containers of
different materials. In addition, systems based on
tare weight or other detection systems merely highlight
the existence of a problem. A more preferable solution
to the problem is a system which simply and
reproducibly delivers all of the contents of a
container to a mixing vessel.
$umma:~ Oe-ehe-lDLGoti Q~
The present invention solves the problem of
incomplete delivery of the contents of a container by
materials handling equipment.
According to the invention, a materials handling
system is provided that comprises a rigid container
having an open upper end and at least one perforate
region which allows the passage of a ~as; a flexible
liner in the container, an upper portion of the
flexible liner beiny adapted for sealing against a side
of the container to create a closed space between the
container and the liner into which a gas can be
injected through the perforate region; means for
grasping and inverting the container; and means for
injecting a gas through the perforate region into the
space between the flexible liner and the container to
evert the flexible liner.
The invention also provides a method for precisely
dispensing the contents of a container, comprising the
steps of providing a rigid container having an open
upper end and at least one perforate region which
allows the passage of a gas, the container having a
flexible liner adapted to be sealed against a side of
the container; sealing the liner against a side of the
container to create a closed space between the
container and the liner into which a gas can be
injected through the perforate region; grasping and
inverting the container; and injecting a gas through
the perforate region in the container into the space
between the flexible liner and the container to evert
the flexible liner.
Other objects, features and advantages of the
present invention will become apparent from the
following detailed description. It should be
understood, however, that the detailed description and
the specific examples, while indicating preferred
em~odiments of the invention, are given by way of
illustration only, since various chan~es and
modifications within the spirit and scope of the
invention will become apparent to those skilled in the
art from this detailed description.
Brief P ~
Figure 1 is a perspective view of the container
with the liner.
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Figure 2 is a view of the bottom of the container
in the robot gripping mechanism.
Figure 3 is a perspective view of the container
gripped by the robot gripping mechanism.
Figure 4 is a perspective view of the container
gripped by the robot gripping mechanism and rotated
180 in order to dispense the contents of the
container.
Eçscr~iQ~~ h~ P~ferr~d ~m~-Q~im=~
A preferred embodimen~ of a container according to
the present invention is shown in Figure 1. Container
1 has open upper end 2, which is adapted to receive a
lid (not shown), Container 1 is specially adapted for
use in an automated manufacturing line. For this
purpose, it is provided with portions which interact
with equipment in the manufacturing line, so that it
can be securely transported to a dumping station and
dumped.
The preferred embodiment of container 1 shown in
Figure 1 has interactive portions at both the top and
bottom. Near upper end 2 is lip 3, which extends
outwardly from the outer surface of container 1. Lip 3
cooperates with robot gripping mechanism 8, as shown in
Figure 3, to serve as a stop against which robot
gripping mechanism 8 rests, and to facilitate sealiny
of liner 6 to container 1. Lip 3 is shown as
continuous. This is a preferred embodiment which
improves sealing of liner 6 by robot gripping mechanism
8. Lip 3 can also be discontinuous. Inverted U-shaped
extensions 4 at the bottom of container 1 interact with
an automated handling system (not shown~ which moves
container 1 between stations in the manufacturing line.
Viewed from the bottom (Figure 2), extension ~ appears
as an outer wall. Supporting ribs 5 extend between the
wall of container 1 and extension g.
Container 1 contains flexible liner 6 in which a
solid material, either free-flowing or gelatinous, is
contained. In a preferred embodiment, liner 6 is not
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permanently attached to container 1, allowing it to be
easily disposed of after container 1 has been emptied
of its contents. The material of liner 6 depends on
the solid material to ~e contained; it is required that
the liner material not react with the solid mat~rial it
contains. In addition, if the solid material is
sensitive to light, liner 6 should not transmit light
of the wavelength to which the material is sensiti~e.
In this case, it is expedient to use a liner made of
multiple layers, preferably three. This ensures that
light does not enter through pinholes in liner 6.
In a preferred embodirnent, liner 6 does not pennit
the passage of a gas. It is, however, possible for
there to be some passage of gas around the edge of or
through liner 6, so long as su~ficient gas pressure is
used to evert liner 6.
Preferably liner 6 is made of a plastic material,
for example, polyethylene, in a thickness between about
2.5 mil and 5 mil. Commercially-available conventional
equipment designed to insert liners into contalners is
used to place liner 6 into container 1. While thicker
liners can be used in principle, they generally cannot
be successfully inserted with the conventional
equipment. It is preferred to use a liner that is
about 2.5 mil thick.
According to the invention, liner 6 is sealed
against a side of container 1 when the contents of the
container are to be dumped. In a preferred embodiment,
liner 6 has cuf~ 7 which can be turned back over open
upper end 2 of container 1. Cuff 7 can be conveniently
sealed against the outside of the container by gripping
the container over cuff 7 with robot gripping mechanism
8 when the contents of container 1 are dispensed. In
this case, liner 6 can be permanently sealed to a side
of container 1. Liner 6 can be permanently sealed to
the inside of container 1.
Liner 6 does not necessarily have to be completely
sealed against container 1. For example, robot
gripping mechanism 8 may only grasp container 1 at
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certain points. In this case, greater gas pressure is
required to evert liner 6. A complete s aling of liner
6 to container 1 is the most efficient embodiment from
the standpoint of the gas pressure required to evert
liner 6.
Container 1 can be made of various materials,
provided they are rigid. For example, it can be made
of metal or plastic, especially polyethylene. It can
expediently be made by injection molding a plastic
material in the desired shape. The container shown in
the figures is of a generally square shape, but could
be various other shapes, for example, round. There is
at least one perforate region in container 1 that
allows a gas to be forced into the space between
container 1 and the liner 6 or that allows the gas to
be withdrawn from this same space. The perforate
region can comprise a hole or preferably a plurality of
holes 9, as shown in Figure 2. It is particularly
preferred that the perforate region be in or near the
bottom of container 1.
Container 1 can be conveyed by an automated
handling system to a dumping station where its contents
are to be dispensed. There it is grasped by robot
gripping mechanism 8, which may be of various types
which are known in the art. When a container adapted
to interact with an automated handling system, such as
the one sho~m, is used, robot gripping mechanism 8 must
be able to lift the container to free it from the
automated handling system ~z-direction movement), it
must be able to move the container over the mixing or
reactor vessel (x-direction movement), and it must also
be capable of rotating about its center axis in order
to dump the contents of the container (pitch and yaw).
Robot gripping mechanism 8 may also be capable of other
movements, depending on the particular situation.
Robot gripping mechanism 8 is adapted to the shape
of container 1 in order securely to grasp it near the
top, just below lip 3. In the preferred embodiment,
robot gripping mechanism 8 securely holds cuff 7 in
place and seals it against the outside of container 1
in the process of grasping container 1. Robot gripping
mechanism 8 then lifts and positions container 1 over a
hopper (not shown) that is located over a mixing or
reactor vessel (not shown). Robot gripping mechanism 8
inverts container 1 so that its contents are dispensed
into the mixing or reaction vessel. In a preferred
embodiment, robot gripping mechanism 8 rotate~
container 1 by 180 to dispense the contents.
After the initial dumping of the container
contents, inflater mechanism 10 having a pliable vacul~m
cup 11 is positioned over hole(s) 9 in the bottom of
container 1. Pliable vacuum cup 11 may be made of
rubber or other similar material. Preferably, robot
gripping mechanism 8 raises container 1 toward inflater
m~chanism ~0, since the robot gripping mechanism
typically has finer movement control than inflater
mechanism 10. Pliable vacuum cup 11 is pressed against
the bottom of container 1, completely covering hole(s)
9 and creating a gas/vacuum-tight seal.
Pliable vacuum cup 11 is connected to a pump (not
shown). Since liner 6 is securely sealed against the
sides of container 1, introduction of low pressure,
high volume gas by the pump into the space between
liner 6 and container 1 forces liner 6 to evert, that
is, to turn inside out, as shown in Figure 4. The gas
may be any inert gas. Air may be used, but it may be
preferable in a clean room situation to use a
containerized gas, for example, N2.
Gas pressure is maintained until liner 6 is fully
everted. When a 2.5 mil thick polyethylene liner is
used, a pump pressure of approximately 50 inches H20 is
necessary to evert liner 6. The pressure will vary,
depending on the thickness of liner 6 and the tightness
of the seal between liner 6 and container 1. In this
way, the entire contents of a rigid container
containing a known quantity of a solid material can be
dispensed into a mixing or reactor vessel.
Alternatively, devices other than pliable vacuum
cup 11 can be used to effect the gas/vacuum-tight seal
of inflater mechanism 10 with container 1. These
include a fixture on the bottom of container 1 that
sealingly engages a fixture on inflater mechanism 10.
These other devices are less preferred, however, since
they introduce an unnecessary level of complexity into
both container 1 and the mating of container 1 and
inflater mechanism 10.
Once the contents of container 1 have been
dispensed, vacuum is applied to draw liner 6 back into
container 1. This prevents liner 6 from becoming
entangled in or soiling the equipment. When a 2.5 mil
thick polyethylene liner is used, a pump pressure of
approximately 50 inches H2O is necessary to pull in
linex 6. Here again the pressure will vary depending
on the thickness of liner 6 and the tightness of the
seal between liner 6 and container 1. After liner 6 is
repositioned inside container 1, the vacuum is released
and inflater mechanism 10 is withdrawn from container
1. Robot gripping mechanism then rotates container 1
by 180~ to return container 1 to its upright position
and replace it on the automated handling system.
After use, container 1 can be refilled with a
precise amount of solid material. If container 1 is to
be refilled with a different material, liner 6 is
removed from container 1 and a new liner is inserted.
While the invention has been described in detail
with respect to particular preferred embodiments, it
should be understood that such description is presented
by way of illustration and not limitation. Many
changes and modifications within the scope of the
present invention may be made without departing from
the spirit thereof, and the invention includes all such
modifications.
